Semiconductor memory devices may be classified mainly into volatile memory devices and non-volatile memory devices. Write speed of volatile memory devices may be rapid, while contents stored therein may disappear at power-off. On the other hand, non-volatile memory devices may retain contents stored therein even at power-off. For this reason, non-volatile memory devices may be utilized to store contents to be retained regardless of whether power is supplied. In particular, as a type of non-volatile memory device, flash memory is applied to large-volume auxiliary memory devices because higher integration density may be achieved with flash memory than conventional electrically erasable programmable read-only memory (EEPROM).
Mobile circumstances may need high integration density, low-power and high-reliability non-volatile memory devices. Upon designing high-speed non-volatile memory devices, AC characteristics associated with the input and output of data/address/control may be addressed. AC characteristics may not be based on characteristics of integrated circuit devices or controllers for controlling integrated circuit devices, but instead may be based on characteristics of channels connecting two or more devices. Therefore, channel characteristics may be considered during high-speed integrated circuit device design.
An example of channel characteristic improvement includes the use of on-die termination (ODT) circuits or off-chip driver circuits. The impedance of signal lines can be adjusted via the ODT circuit.